Tottuwrpmt



H DETERGENT COMPOSITIONS Richard D. Stayner,1Berkeley, Califi, assignorto California Research Corporation, San Francisco, Calif., a corporationof Delaware 6 Claims. .(Cl. 252-137) No Drawing.

This inventionrelates to improved anionic synthetic detergentcompositions containing as their only effective detergent ingredient awater-soluble alkyl aryl sulfonate. More particularly, the inventionrelates to those synthetic detergent :compositions which contain aWater-sluble alkyl benzene sulfonate as their sole effective ingredient,and which produce presistent foams of good quality when employed indilute aqueous solutions to wash soiled fabrics. i i

:The average user of detergents insists on buying detergentlmaten'alscapable of producing a substantial volume of suds, owing to a deeplyingrained belief that the formation of copious suds or foam is alwaysaccompanied by a good detergent action. The majority of users ofdetergent products, whether housewives or commercial laundry operators,continue to prefer those materials which produce a dense foam made up bysmall-size bubbles and giving the familiar feeling of cream-likesoapsuds on contact with the hand.

. Because at the present time a large volume of household washing isdone by housewives in non-automatic, agitatortype washing machines, theability of a detergent composition to produce stable foam under staticconditions is not a criterion that it would secure a lasting preferenceof the consumer. Actually the foam, in addition to being similar inphysical appearance to soapsuds, must be persistent throughout thewashing cycle, despite the continuous agitation of the contents of thebowl or tub of the washing machine, the presence of soil, laundry, etc.At low use concentrations in soft water, this requirement ofwfoampersistence cannot, as a rule, be attained in the case of alkyl arylsulfona e type detergents, and this inability of producing persistentfoams is best exemplified in the use of sodium salts of C9-C1s monalkylbenzene sulfonic acids, otherwise very efficient as detergents. As amatter of fact, the suds produced with solutions of detergentcompositions containing such sulfonates as their major activeingredients are extremely short-lived and last but a few minutes,usually from 1 to less than 10 minutes depending upon such factors as:hardness of water, amount of the activesulfonate in the formulation,type and amount of soil present, concentrationof the wash solution andtemperature of this latter.

.The C9-C1s monoalkyl benzene sulfonates, the improvement of foamproperties whereof is particularly consideredin the presentspecification, are usually prepared byreacting benzene with a long-chainCg-Cis aliphatic alcohol, or with a Gil-C18 olefin produced, forinstance, by cracking petroleum hydrocarbon gases and polymer: izing thegaseous olefins thus formed, or with an alkyl halide obtained bychlorinating petroleum hydrocarbons of the boiling range of kerosene;sulfonating the resulting alkyl benzene compounds with sulfuric acid,chloro sulfonic acid or sulfur trioxide; neutralizing the resultingsulfonicacid with a base (eg., NaOH or NazCOs); and, finally,- dryingthe neutralized slurry product (e. g., by spray-drying) to the desiredparticle form and size. Detergent compositions containing sodium C9-Cmalkyl ben- 2 zene sulfonate as their major organic detergent ingredientordinarily contain, in addition, from 50 to 90% by weight of inorganicalkaline builders such as polyphosphates and/or sodium sulfate. In theconventional sodium alkyl benzene sulfonate detergent compositionsemployed for laundering and household washing, from 20 to 50% by weightof these inorganic alkaline builder constituents is constituted bysodium sulfate, which is either present in the product as a result ofthe neutralization of unreacted sulfuric acid in the sulfonationreaction mixture, or

is added to suit the particular detergent product specification. Thebalance of the builder portion, from to 20% by weight thereof, is eithersodium trlpolyphosphate or tetrasodium pyrophosphate, or a mixture ofthe two in any appropriate weight ratio. Usually, sodium silicatebuilders in amounts of the order of 5% by weight of the total solids arepresent in these detergent formulations. in addition, these sulfonatedetergent compositions may contain other conventional additives such assodium carboxymethyl cellulose extender, optical bleach, perfume, etc.in small amounts readily determined by those skilled in the art to suitthe requirements of each particular formulation.

A number of additives have been proposed in the past for the purpose ofpromoting foam formation in aqueous wash solutions of alkyl benzenesulfonate detergent compositions and imparting the desired persistenceto this foam. For instance, small amounts of alkylol amides of fattyacids, e. g., isopropanol amide of lauric acid and ethanol amide oflauiic acid, have been blended into these sulfonate detergentcompositions. However, while their addition improved the desired foampersistence, their presence in the sulfonate detergent product causedstickiness and caking of the particles during the spraydrying step ofthe detergent manufacture and in the storage of the finished particulateproduct. Furthermore, foams produced by the alkyl benzene sulfonatedetergent compositions containing such amides do not attain the desiredquality of soapsuds with respect to color, size of the bubbles,flexibility and wetness. N-alkyl-p-alanines have been suggested as foamstabilizers. However, the presence of these alanines in alkyl benzenesulfonate detergent compositions causes a reduction in the detergentpower thereof, and their application must be, therefore, ruled out.

I have now found that very satisfactory foam characteristics can beimparted to a detergent composition, in which the major active organicdetergent ingredient is a watersoluble alkyl benzene sulfonate in theamount equal to from 10 to 50% by weight of the total content of solids,by introducing into such a composition a small quantity of N-alkylimino-diacetic acid wherein the alkyl chain contains from 8 to 18 carbonatoms. Very satisfactory foams can be obtained with the aqueoussolutions of detergent compositions wherein the predominant organicdetergent ingredient is an alkyl benzene sulfonate, containing from 0.5to 10% by weight of N-alkyl imino-diacetic acid additives, based on thetotal content of solids (or from 5 to 20% based on the weight of theactive sulfonate ingredient), not only with respect to the volume andquality thereof, but also with respect to its persistence throughout theentire agitation cycle in the washing machine. The greater is theconcentration of the additive in the detergent composition, the betteris the foam persistence. In general, an abundant foam of good qualityand a high degree of persistence can be obtained by adding to the alkylbenzene detergent composition from 2 to 4% (by weight of the totalsolids) of an N-alkyl imino-diacetic acid, though smaller or greateramounts may be required with varying water hardness, concentration andtemperature and quantities of individual ingredients within thedisclosed operative ranges thereof.

3 This additive, which for the sake of brevity, will be termed hereafterN-alkyl diglycine, is soluble. in water I and nonvolatile, both of theseproperties representing a decided advantage over the previously proposedadditives positions containing sodium C9-C18 monoalkyl benzene sulfonateas the major organic detergent ingredient.

This sodium salt is easily prepared by a simple one-step reaction of astraight-chain Cs-Crs alkyl amine with sodium .chloroacetate. Anexcellent source of fatty amines for the preparation of effectiveN-alkyl diglycines is offered by'coconut fatty acid amines ordinarilycontaining about 15% of amines with less than 12 carbon atoms in thealkyl chain, about 45% of C1; amine, and about 40% of amines with morethan 12 carbon atoms in the alkyl chain. I have found that whilegenerally watersoluble alkaline salts of N-alkyl diglycines containingfrom Ca-Cia carbons in the alkyl chain will secure the desiredimprovement in the foam properties of an alkyl benzene sulfonatedetergent composition, particularly satisfactory results will beobtained with water-soluble alkaline salts of N-alkyl diglycinescontaining from 10 to 16 carbon atoms in the alkyl chain, the bestresults being secured with water-soluble alkaline salts of N-alkyldiglycines containing from 12 to 14 carbon atoms in the alkyl chain.

' The N-alkyl diglycine may be introduced into the sulfonate detergentcomposition either before the'neutralization of thesulfonic'acid-unreacted sulfuric acid mixture or it maybe added as acorresponding water-soluble salt to the neutralized slurry, this lasttechnique being preferred. Upon blending of the additive with theneutralized slurry, the mixture is reduced to the desired particle sizeand foam, e; g., by spray-drying. The N-alkyl diglycine may be alsoadded to alkyl benzene sulfonate detergent essentially free of inorganicsalts and formulated as concentrated liquids with water or otherappropriate solvents.

As pointed out hereinbefore, the alkyl benzene sulfonate detergentcompositions, foam properties of which can be improved by the additionof N-alkyl diglycine additives according to the invention, may containfrom 10 to 50% by weight of organic detergent ingredients, at least 50%whereof is constituted by a water-soluble salt of a Gil-C18 monoalkylbenzene sulfonic acid, and preferably of a C12-C15 monoalkyl benzenesulfonic acid, and preferably of a Ora-C monoalkyl benzene sulfonicacid. The term water-soluble salt employed hereinabove includesinorganic alkaline metal salts, alkaline earth metal salts such asmagnesium, ammonium salts, and organic alkyl amine and alkylol aminesalts, exemplified by triethanol and diethanol amine salts. Minoramounts of anionic and non-ionic organic detergents may be present inthe formulations, the foam persistence of which is improved by theaddition of N-alkyl diglycines, e. g., alkyl sulfates, polyglycol ethersof alkyl phenols. Ordinarily, the alkyl benzene sulfonate detergentcompositions containing an N-alkyl diglycine additive are dissolved inwater to form solutions of 0.1 to

. 0.4% concentration, conventionally employed in thelaunsolidconstituents thereof. have received an addition of N-alkyl diglycine inthe amounts of from 0.5 to 1.0%, and, preferably from 2 to 4%, based onthe weight of the total solids, the aqueous wash solutions of theseheavy-duty compositions in non-automatic, agitator-type washing machinesform dense, soap-like suds, which persist throughout the entire washingcycle, i. e., up to 20 minutes and often longer.

The flexible texture of the foams thus produced resembles that of thebetter fatty acid soaps: They are light in color, and are made up ofsmall-size bubbles agglomerated to a cream-like consistency. In contrastto a number of other anionic detergent compositions, the

foams produced by alkyl benzene sulfonate detergent compositionsimproved in accordance with my invention do not buildup astifi centralring of dry and frosty foam around the agitator shaft in the tub of thewashing machine. Furthermore, the presence of an N -alkyl diglycineadditive imparts a slippery, soap-like feel to the wash solution, aproperty sought for by the housewife.

Moreover, a highly attractive characteristic of the improved detergentcomposition of the invention is its emollient effect upon the skin ofthe operator due to the presence of the N-alkyl diglycine additive.Whereas quite often housewives and laundry workers handling anionicdetergent compositions complain of their drying actionwhich sequestersoil from the skin and causes cracking and fissuring thereof, thisadverse action has not been observed in the numerous test runs effectedwith the alkyl benzene sulfonate compositions containing salts ofN-alkyl diglycines in accordance with the present invention. I Severalseries of test runs were carried out to evaluate: the quality andpersistence of foams produced byalkyl benzene sulfonate detergentcompositions'containing- N alkyl diglycine additives in accordance withthe invention. In a representative test series, the N-alkyliminodiacetic acid additive (N-alkyl diglycine) was prepared as follows:51 g. of lauryl amine, 21 g. of NaHCOz, and 25 ml. of isopropanol wereplaced in a 500 ml. round-bottomedflask equipped with a thermometer,stirrer and addition funnel. The mixture was heated to 150 F., whereupona solution of 59 g. of sodium chloroacetate in 75 ml. of water was addeddropwise for a period of about 15 minutes, taking care to maintain thetemperature without heating at 150175 F. Upon completing the addition,the solution was refluxed for at least 3 hours until the evolution ofCO2 ceased. The final solution (165 g'.) contained 'g. of N-laurylimino-diacetic acid as the monosodium salt at pH 7.5. The sulfonatedetergent composition employed in this test series contained sodiumC12-C15 polypropylene benzene sulfonate (prepared by the processdisclosed by A. H. Lewis in U. S. Patent'#2,477,- 383) as its soleorganic detergent ingredient in an amount from 20 to 30% by weight, from2 to 3% by weight of a N-lauryl diglycine, the remainder to make upbeing sodium tripolyphosphate (or a mixture of sodium tripolyphosphateand tetrasodium pyrophosphate) and sodium sulfate. The tests consistedin agitating identical loads of soiled cotton laundry in the bowl of anagitator-type non-automatic domestic washing machine filled with adilute aqueous solution of the detergent containing an effective amountof an N-alkyl diglycine additive. Solutions of 0.15% concentration ofthese detergent formula-- tions in soft water (50 p. p. m.; CaCOs:MgCOa=2:1') were maintained at the same temperature throughout the testruns, and the agitation was carried out in each instance for 20 minutesunder identical conditions.

The results of this series of test runs are tabulated in Table I.Persistence of the foam after 2, 5, 10, 15 and 20 minutes of operationis defined in terms of foam height (in inches) and coverage, i. e., theextent of the tub surface covered by the foam, in'per cent. The datafoam persistence or none at all. On the other hand, dilute cottontowels, to each of which had been pinned a strip aqueous solutions ofthose detergent compositions whi h of cotton, uniformly soiled with anoily soil. In each contain the diglycine additive display excellent foampertest run agitation was carried out for the same length of sistence;and. the foam produced by these wash solutions time and under identicalconditions. After the complelasts 20 minutes and longer, withoutsubstantial reduction 5 tion of each test run, the swatches wereremoved, and the of volume .or alteration of foam quality, in spite ofthe degree of whiteness (detergency) obtainedwas measured Table I creamydense suds, made up of small size bubbles, pro- Size of the"foambubbles, and the feehor body of the foam produced by sulfonatedetergent formulations containing an N-alkyl diglycine, favorablycompare with the 'duced by a 0.25%solution of aphosphate-built, tallow'fatty acid soap (run #23 of the table) and are definitely; superior tolacy, rapidly decaying foam of alkyl benzene sulfonate detergentcompositions which did not contain diglyciue additives (runs#l, 3, 5;. 9of the table).

Wetness'and mobility of the foam are likewise satisfactory: samples,placed upon a vertical glass surface, slide down rapidly as compared toseveral samples of foams produced by dilute solutions of commercialalkylg' sulfate-alkyl benzene sulfonate detergent compositions whichappear to be dry and frosty, and cling to the glass"""' surface. I LIncreasing water hardness appears to increase the foam jf persistence,and the like effect is observed on replacing sodium sulfate builder inthe sulfonate detergent com-i position by magnesium sulfate, However, ineither in a stance, the detergency of the wash solution isadversely]affected, and a greater concentration of the active detergent sulfonatecomponent may be required.

At this point, it maybe noted that it is possible to com- 457/ bine withadvantage into the same sulfonate detergent formulation an N-alkyldiglycine: additive which improves foam persistence and foam qualitywith alkylol amides off higher fatty acids, such as isopropanol amide oflauric acid or ethanol amide of lauric acid, which, in addition to beinggood foaming agents, tend to enhance detergency. Heretofore, it wasimpossible to spray-dry a' neutralized slurry of alkyl benzene sulfonatecontaining 25% by weight or more (based on the total solids) of the,active sulfonate detergent and as little as 2% by weight of an alkylolamide of a higher fatty acid, without running into the problems of: (1)stickiness inthe spray-drying step (the material adheres to the. wallsof the spray-drying chamber instead of readily dropping into thehopper); and (2) caking upon storage of the spray-dried product. 50 Forinstance, the neutralized slurry containing 20%. by weight of sodiumalkyl benzene sulfonate and 2% by weight of isopropanol amide of lauricacids was difficult to prayry. and pon p ng d sto ge n a humid;atmosphere'caked' badly, and failed to pass, the requiredspecifications. On the other hand, a slurry containing 30% by weight ofsodium alkyl benzene sulfonate and 3% by weight of the sodium salt ofN-lauryl diglycine presented. no problem in the course of spray-dryingand satisfactorily passed the caking specification after similar storagein a humid'atmosphere. Thus, by aproper selw tion of the twat-mm imroving additives (Nalkyt diglycine and-alkylol amide ofa higherfatty-acid), it will be possible to eliminate theaforementioneddifficulties of manufacturing and storage and to impartbetter properties.

to sulfonate detergent formulations, 'so as to make them more attractivefor the consumer. 1 a

It is. to be understood that the aforegiven description and experimentaldata are merely illustrative of the'invention; and-that it may bemodifiedwithout essential departure from the spirit and scope thereof,provided that such modifications fall within the scope of the appendedclaims.

Iclaim; V p

1. A- detergent composition, characterized by a high degree ofpersistence of its foam under conditions of agi tation in diluteaqueous. solutions, consisting essentially of from 10 to' 50% by weight,based on the total content of solids in said composition, of awater-soluble salt of a C9-C1s monoalkyl benzene sulfonic acid as itsmajor or? ganic detergent ingredient, from 0.5 to 10% of a watersolublesalt of an N-alkyl imino-diacetic acid wherein the alkyl group. containsfrom 10 to. 16 carbon atoms, the

remainder-to make up being essentially inorganic salt detergentbuilders.

A detergent composition, characterized by a high degree of persistenceof'its foam under conditions'of agitation in dilute aqueous solutions,consisting essentially of from 10 to 35% by weight, based on the totalcontent of solids in said composition, of a water-soluble salt of aC9-Cl8 monoalkyl benzene sulfonic acid as its major organic detergentingredient, from 2 to 4% 'of a watersoluble salt of an N-alkylimino-diacetic acid wherein the alkyl group contains from 10 to 16carbon atoms, and the remainder to make up 100% being essentiallyinorganic salt detergent builders.

3. A detergent composition, characterized by a high degreeofpersistenceof its foam under conditions of agitation indilute aqueous solutions,consisting essentially of 7 -from 10 to 50% by weighhbased on the totalcontent of V solids in said composition, of a water-soluble salt of a"Ga-Cm monoalkyl' benzene sulfonic acid as its major organic detergentingredienh'fr'om 0.5 to 10% of a water- ,soluble salt of an N-a-lkyl'imino-diacetic acid-wherein the alkyl group contains from 10 to 16carbon atoms, and the remainder/to make up 100%.being essentiallyinorganic salt detergent builders, of which from 10 to 50% is sodiumsulfate. I 4. A detergent composition, characterized by a high degree ofpersistence of its foam under conditions of agitat-ion in dilute aqueoussolutions, consisting essentially of from 10 to 50% by weight, based onthe total content of solids in said composition, of a water-soluble saltof a 'Cs-C monoalkyl benzene sulfonic acid as its major organicdetergent ingredient, from 0.5 to 10% of a watersoluble salt of anN-alkyl imin -diacetic acid wherein the alkyl group contains from 10 to16 carbon atoms, from 10 to 45% of sodium sulfate builder, and theremainder to make up. 100% being essentially inorganic alkalinepolyphosphate builders.

5. A detergent composition, characterized by a high degree ofpersistence of its foam under conditions of agitation in dilute aqueoussolutions, consisting essentially from 10 to 50% by weight, based on thetotal content of solids, in said composition,,of"a water-soluble salt ofa Cs-C1 monoalkyl benzene sulfonic acid as its major organic detergentingredient, from 0.5 to 10% of a watersoluble salt of an N-alkyljimino-diacetic acid wherein the alkyl group contains from 10 to 16carbon atoms, from 10 to 45% of sodium sulfate builder, and theremainder being essentially a mixture of sodium tripolyphosphate andtetrasodiurn pyrophosphate.

6. A detergent composition, characterized by a high degree, ofpersistence of the foam of its dilute aqueous i solutionsunderconditions of agitation and in the presence of soil, saidcomposition consisting essentially ,of a'water-so'luble salt of a Cs-Cia monoalkyl benzene sulfonic acid as its major organic detergentingredient normally tending to sequester oil from human skin and toReferences Cited in the file of this patent canse irritation thereof,am} from 5 to 20%, based on the UNITED STATES PATENTS weight of saidsulfonlc acid salt, of a water-soluble salt of an N-alkyl imino diaceticacid, in which the alkyl 210973864 P 1937 group contains from 10 to 16carbon atoms as a foam 5 2477383 Lewls July 1949 persistence improverand an inhibitor of skin irritation. 2619467 Isbeu 25, 1952

6. A DETERGENT COMPOSITION, CHARACTERIZED BY A HIGH DEGREE OFPERSISTENCE OF THE FOAM OF ITS DILUTE AQUEOUS SOLUTIONS UNDER CONDITIONSOF AGITATION AND IN THE PRESENCE OF SOIL, SAID COMPOSITION CONSISTINGESSENTIALLY OF A WATER-SOLUBLE SALT OF A C9-C18 MONOALKYL BENZENESULFONIC ACID AS ITS MAJOR ORGANIC DETERGENT INGREDIENT NORMALLY TENDINGTO SEQUESTER OIL FROM HUMAN SKIN AND TO CAUSE IRRITATION THEREOF, ANDFROM 5 TO 20%, BASED ON THE WEIGHT OF SAID SULFONIC ACID SALT, OF AWATER-SOLUBLE SALT OF AN N-ALKYL IMINO DIACETIC ACID, IN WHICH THE ALKYLGROUP CONTAINS FROM 10 TO 16 CARBON ATOMS AS A FOAM PERSISTENCE IMPROVERAND AN INHIBITOR OF SKIN IRRITATION